It is known in the tiling field that when tiling counter tops, cabinets or the like, many times cracking of the tile cap is incurred. Therefore it is desirous to provide a method and/or apparatus which eliminates or highly reduces the occurrence of the above mentioned problem.
In the past attempts have been made to reduce the likelihood of cracking the adhesive and/or the tile cap. Such as U.S. Pat. No. 5,060,438, wherein they provide a method and apparatus which includes a channel shaped cap support strip for a cap strip of a tiled counter top which is formed with a plurality of projecting tongues that are embedded within the adhesive that overlies the horizontal surface of the counter, with the body of the cap support strip channel being nailed to the vertical surface of the front of the counter. The tongues, embedded in the adhesive that holds the tile in pace, hold the upper part of the cap support strip securely tied to the counter top and "in theory" helps to prevent cracking of the tile caps, however in practise this and other prior art apparatus's have proved un-satisfactory due to the traveling stress in both walls and floors which is transferred to the tile cap.
Traveling stress in both walls and floors have been recognized and addressed in the prior art in the ceramic tile trade since its beginning. Most workman in the trade today are cognizant of the various causes and conditions that create this problem but are helpless to minimize or alleviate them.
In relatively recent times traveling stress in the rail of mud-set countertops, has been an increasing problem. The inventors of the present invention have consulted with every knowledgeable source immediately available, and the best answer found was both vague and ambiguous. This is to that the consensus of opinion is that stress is caused by movement. That kind of answer gives one little satisfaction when standing and looking at a countertop with stress-cracked tile running half way around it, as if a pair of giant hands had torn those tiles apart as easily as a person tears a piece of newspaper.
With this in mind, we have analyzed the possible sources of movement starting at the bottom. First, there is the compaction of the soil under a post footing. The moisture in the soil could dry out with a possibility of a 1/32" movement downward. Second, the redwood block under the post sitting on the footing could compress 1/32". Third, the post itself could shrink 1/32". Fourth, the beam on the post could shrink 1/32". This next item has a potential for being the worst culprit of all the others put together, that being 3/4" flakeboard sub-flooring. The reason for this is, even though bonding resins are waterproof, the wood fibers are not. When left out in the weather before the roof is on, they will expand 1/4". This doesn't affect its structural integrity, however, covering it with underlayment and setting cabinets on it is tantamount to setting cabinets over carpet pad and in a worst scenario, the potential for movement is up to 3/8".
In the prior art, most kitchen cabinets in the past were custom fabricated as a single unit built from solid 3/4" wood or 3/4" plywood, while today's cabinets are primarily modular units and the only things that are 3/4" solid wood are face frames and doors. The side panels are 3/8" particleboard and the back panels are 1/4" masonite. The bottoms and shelving are 1/4" masonite, veneered. In the past, face frames were nailed and glued and had corner and angle blocking. Most modular units today are glued and might have a few pins or staples in them. One can readily see that these newer cabinets do not contribute to a stable base for the mud countertops. The tile manual recommends slash cutting in 3/4" plywood tops or 1'.times.6" boards placed at 1/4 intervals. However, in the opinion of many workman it can be argued that a solid 3/4" plywood top contributes more to the structural integrity of the whole, especially on the front of the cabinet because of the fact there is a 4" toe kick at the base of the cabinet. This means the face of the cabinet is cantilevered and is getting all its support from the side panels. This is especially true on overhanging countertops with a serving area. In the latter, it is imperative that, in order to get any support at all, the korbels be aligned over the modular unit side panel joints.
Two other points must be considered when discussing particleboard: first, the fact that particleboard resin used in the manufacturing process contains formaldehyde as a drying agent, and a 4'.times.8' sheet of particleboard can shrink in size up to 1/8" during the curing. It also takes up moisture very readily under extremely damp conditions. In either case, there is a possibility of popping its own glue joints. Second, there is a tendency to buckle under stress. Now that the movement that can transpire from the ground to the underlayment and the variables involved in the cabinet itself are understood, next comes the big question! How does all this downward vertical movement relate to stress in the rail?
This can best be answered by visualizing a sectional view of a cabinet with a tile countertop. The first thing that happens is a downward movement of the face of the cabinet caused by one or more of the aforementioned possibilities. At this point the stress is felt only on the face of the cabinet, but at the same time, is magnified by the fact that the pivot point for the stress is at the base of the cabinet where it meets the toe kick, which is secured to the floor. There is no downward stress on the back of the cabinet, as it is firmly secured to the outside wall, where it remains stable.
Now visualize the rough top, which is essentially an elongated rectangular member that is firmly secured to the back wall of the cabinet and the hardwood face frame. The stress in now transferred to the rough top, and by its downward movement, changes our rough top into a parallelogram when viewed from a level plane with the pressure point being the top front corner, which essentially acts as a wedge. At this point, one must bear in mind that the mud-set ceramic countertop is a rigid, monolithic unit without tolerance for flexibility. At this point the stress is telegraphed through the convention prior art A-metal and the mud backing on the rail apron. Next, a basic law of physics comes into play, the law of compound leverage. The stress is transferred vertically to the top of the rail seeking the weakest point to expend its energies and is on the tail side of the rail. The origin of this stress usually starts in the middle of an area that has the most severe movement. Then it goes trough the aforementioned steps and travels in both directions of the rail until its energies have been released.
It is therefore desirable to provide means to remove and keep the stress generated by any one or any combination of the above described stresses from reaching the tile corner cap to reduce its potential to crack, and it is this problem which the present invention addresses.